Wiki creation logs containing backslashes are breaking JSON serialization

Reproduction steps:

• Setup the servlet engine to support backslashes in URLs
• On administration > Edition > Name strategies remove "\" from the forbidden characters in page names
• Create a new empty template wiki and leave it empty
• Go in the template wiki and create a page with a "\" in its path
• Create a new wiki from the template you just edited

Expected result:

• The wiki creation UI displays that it's successfully created

Obtained result:

• The UI get stuck very quickly during the wiki creation

Old description with other steps:
We serialize in JSON all the job logs to be able to display them to the users, but apparently when a stack trace concerning a file is outputted in the logs, it break JSON serialization on Windows.
See the attached JSON.

Reproduction steps:

• Create a page with the following snippet:

  {{velocity}}
  #if ($xcontext.action == 'get' && "$!{request.outputSyntax}" == 'plain')
    #set($discard = $response.setContentType('application/json'))
    #set ($message = "File not found exception: C:\MyFile\Somewhere\There")
    #set ($logs = [$escapetool.xml($message)])
    #set($map = {'wikiId':"myId", 'logs':$logs})
    $jsontool.serialize($map)
  #end
  {{/velocity}}
  

• Call the page with get action and ?outputSyntax=plain, e.g.:

  http://localhost:8080/xwiki/bin/get/Test/?outputSyntax=plain
  

Expected result:

• the produced JSON is correct

Obtained result:

• the following broken JSON:

  {"wikiId":"myId","logs":["File not found exception: C:
  MyFile
  Somewhere
  There"]}
  

Edit: actually the snippet is even easier to write:

{{velocity}}
#set ($message = "File not found exception: C:\MyFile\Somewhere\There")
$jsontool.serialize($message)
{{/velocity}}

shouldn't create any line break.